JP6627488B2 - Image forming apparatus, correction information generation program, and correction information generation method - Google Patents

Description

  The present invention relates to an image forming apparatus, a correction information generation program, and a correction information generation method.

  In recent years, electrophotographic devices such as laser beam printers and LED (Light Emitting Diode) printers have been widely used. With the spread of PCs (Personal Computers), low-cost page printers have been demanded. On the other hand, laser beam printers can realize exposure control with a simpler configuration than LED printers. Thus, an inexpensive electrophotographic apparatus can be provided. In addition, since the processing of a photographic image can be performed by an individual due to a reduction in the price of a high-performance PC, a printer capable of printing a photographic image with high resolution is also required.

  There is an image input / output system that outputs multi-value image data read by an input device such as a scanner or a digital camera to an output device such as a printer or a display. In an image input / output system, multi-valued (for example, 256 gradations in 8-bit accuracy) read by an input device is converted into image data of a number of gradations that can be output by an output device, and the image data is converted into pseudo data. As a method of expressing a continuous tone, there is a method called pseudo halftone processing. As a result of increasing the resolution by the pseudo halftone process, density unevenness may appear in the halftone processed image. For example, the density unevenness refers to a streak that appears thinner and whiter than others, or a streak that is darker than others and looks like a line is drawn. Density unevenness is caused by the charge distribution of the electrophotograph, and FF control of the light amount has been required to correct a vertical streak generated according to the state of the charge distribution.

  In Patent Document 1 (Japanese Patent Application Laid-Open No. 2007-118194), a technique for improving the accuracy of adjusting the lighting amount of each lighting element of the LED array system by using an LUT (Look Up Table) for correcting the light amount variation of each LED. Is disclosed. However, since the charge distribution changes depending on conditions such as temperature, humidity, and aging of the device, it is hard to say that correction using the LUT can control the light amount appropriately in accordance with these conditions. Since the charge distribution changes depending on conditions such as temperature, humidity, and aging of the device, there is a demand to easily create a light amount correction table for correcting vertical streaks. In order to create a correction table, it is important that a posture when reading a chart including a test pattern is preferable.

  Patent Literature 2 (Japanese Patent Application Laid-Open No. 2006-31079) discloses a technique of correcting image data by rotating image data obtained by reading a chart. Further, in Patent Document 3 (Japanese Patent No. 4994203), a technique for obtaining a preferable color reproducibility for read image data and printed matter, which can broaden a user setting condition to be applied to correction of a scanner difference, is disclosed. It has been disclosed.

  However, in the related art, there is a problem that it is difficult to create suitable correction information for correcting a vertical streak of an electrophotograph caused by a charge distribution. In general, it is known that the greater the number of read gradations, the more the effect of density unevenness can be reduced. However, since a scanner having a large number of read gradations (for example, 16 bits) is not widely used, even a scanner having a small number of read gradations (for example, 8 bits) corrects the vertical streak. It is important to create a correction table for this. In the related art, it is difficult to create a suitable correction table in a scanner having a small number of read gradations.

  The present invention has been made in view of the above, and an object of the present invention is to create preferable correction information for correcting a vertical streak of an electrophotograph caused by a charge distribution.

In order to solve the above-described problems and achieve the object, an image forming apparatus according to the present invention includes an image reading control unit that controls an image reading unit that reads a chart including a pattern represented by a pseudo halftone image, and a reading area. A correction information generation unit that generates correction information for correcting the light amount at the time of exposure, based on a plurality of image data obtained by reading the chart in which the position of the pattern is changed a plurality of times , Wherein the chart includes position specifying information for specifying the position of the pattern in the reading area, and the pattern includes the pseudo halftone image in at least one or more modes for characters and graphics. Is represented, the correction information generation unit, based on the position identification information, superimpose a plurality of the image data so that each pattern matches, Based on the superimposed image data by superimposing the image data of the number, and generates the correction information of each of the modes.

  Advantageous Effects of Invention According to one aspect of the present invention, there is an effect that it is possible to create suitable correction information for correcting a vertical streak of an electrophotograph caused by a charge distribution.

FIG. 1 is a diagram illustrating an example of an external configuration of the image forming apparatus according to the first embodiment. FIG. 2 is a diagram illustrating a configuration example of the reading unit according to the first embodiment. FIG. 3 is a diagram illustrating a configuration example of the image forming unit according to the first embodiment. FIG. 4 is a diagram illustrating an example of a chart according to the first embodiment. FIG. 5 is a diagram illustrating an example of setting a chart according to the first embodiment. FIG. 6 is a diagram illustrating an example of setting a chart according to the first embodiment. FIG. 7 is a diagram showing an example of setting a chart according to the first embodiment. FIG. 8 is a diagram illustrating an example of setting a chart according to the first embodiment. FIG. 9 is a diagram illustrating an example of setting a chart according to the first embodiment. FIG. 10 is a diagram illustrating an example of setting a chart according to the first embodiment. FIG. 11 is a block diagram illustrating a hardware configuration example of the image forming apparatus according to the first embodiment. FIG. 12 is a block diagram illustrating a functional configuration example of the image forming apparatus according to the first embodiment. FIG. 13 is a diagram illustrating an example of calculating an average value of luminance in the main scanning direction according to the first embodiment. FIG. 14 is a diagram illustrating an example of the average value of the luminance change according to the first embodiment. FIG. 15 is a diagram illustrating an example of a halftone processed image corresponding to the luminance change illustrated in FIG. FIG. 16 is a flowchart illustrating an example of the flow of the correction information generation process according to the first embodiment. FIG. 17 is a diagram illustrating an example of a chart including a pattern represented by a pseudo halftone image of a plurality of colors according to the second embodiment. FIG. 18 is a diagram illustrating an example of a chart including a pattern represented by a pseudo halftone image in a plurality of modes according to the second embodiment.

  An embodiment of an image forming apparatus, a correction information generation program, and a correction information generation method according to the present invention will be described below with reference to the accompanying drawings. The present invention is not limited by the following embodiments.

(Embodiment 1)
[External Configuration of Image Forming Apparatus]
The external configuration of the image forming apparatus according to the first embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating an example of an external configuration of the image forming apparatus according to the first embodiment.

  As shown in FIG. 1, the image forming apparatus 100 includes a reading unit 201, an image forming unit 202, an image processing unit 203, a display unit 204, and an input unit 205. The reading unit 201 reads (scans) a recording medium such as a document. The image forming unit 202 forms an image on a recording medium such as printing paper. The image processing unit 203 performs various types of image processing. The details of the processing by the reading unit 201, the image forming unit 202, and the image processing unit 203 will be described later.

  The display unit 204 includes a liquid crystal panel, a touch panel, and the like, and displays and outputs various information. For example, the display unit 204 displays a recommended number of readings, a reading method, and the like when reading the chart. Details of the chart will be described later. The input unit 205 includes hard keys and the like, and receives inputs of various information. For example, after confirming the recommended number of readings displayed on the display unit 204, the user operates the input unit 205 to input the number of readings when reading the chart.

[Configuration of Reading Unit]
Next, the configuration of the reading unit 201 according to the first embodiment will be described with reference to FIG. FIG. 2 is a diagram illustrating a configuration example of the reading unit 201 according to the first embodiment.

  As shown in FIG. 2, the reading unit 201 includes an image reading unit 301, a document table 302, an automatic document feeder (ADF: Automatic Document Feeder) 303, a first document scanning body 304, and a second document. A scanning body 305, an optical lens 306, and a photoelectric conversion element (CCD: Charge Coupled Device) 307 are provided.

  The automatic document feeder 303 is supported on the upper surface of the document table 302 so as to be openable and closable with respect to the document table 302, and is mounted with a predetermined positional relationship with respect to the upper surface of the document table 302. The automatic document feeder 303 performs an operation of automatically placing a document on the document table 302. In this embodiment, the original is directly set on the original platen 302 without using the automatic original feeder 303, and the image reading unit 301 reads the original.

  The image reading unit 301 is arranged below the document table 302 for inputting image information of a document placed on the document table 302. The image reading unit 301 includes a first original scanning body 304, a second original scanning body 305, an optical lens 306, and a photoelectric conversion element 307 that reciprocate in parallel along the lower surface of the original table 302.

  The first original scanning body 304 has an exposure lamp for exposing the surface of the original, and a first mirror for deflecting a reflected light image from the original due to the exposure of the original in a predetermined direction. Reciprocating in parallel at a predetermined scanning speed while maintaining a constant distance from the lower surface of the. The second document scanning body 305 includes a second mirror and a third mirror for further deflecting a reflected light image from the document deflected by the first mirror of the first document scanning body 304 in a predetermined direction. , And reciprocates in parallel while maintaining a constant speed relationship with the first document scanning body 304.

  The optical lens 306 reduces the reflected light image from the document deflected by the third mirror of the second document scanning body 305, and forms the reduced light image at a predetermined position on the photoelectric conversion element 307. The photoelectric conversion element 307 sequentially performs photoelectric conversion of the formed optical image and outputs an electric signal.

  The photoelectric conversion element 307 reads a black-and-white image or a color image existing on the surface of the document, and outputs line data obtained by color separation into R (Red), G (Green), and B (Blue) color components. This is a color CCD line sensor. The image information of the document converted into RGB electric signals by the photoelectric conversion element 307 is sent to the image processing unit 203.

[Configuration of Image Forming Unit]
Next, the configuration of the image forming unit 202 according to the first embodiment will be described with reference to FIG. FIG. 3 is a diagram illustrating a configuration example of the image forming unit 202 according to the first embodiment. FIG. 3 illustrates a cross-sectional configuration of the image forming unit 202 by electrophotography.

  The image forming unit 202 forms yellow (Y), magenta (M), cyan (C), and black (K) toner images on the peripheral surface of the plurality of image forming bodies, respectively, and transfers these to the intermediate transfer body. This is a color image recording apparatus in which transfer is performed by superimposing (primary transfer), and then retransferred (secondary transfer) to a transfer material.

  A transfer belt 14, which is a belt-shaped intermediate transfer member, is a CMYK image forming unit including a photosensitive drum 10, a charger 11, an exposure optical system 12, a developing device 13, and a cleaning device 20. The unit 50Y, the unit 50M, the unit 50C, and the unit 50K are arranged from the upstream side in the rotation direction of the transfer belt 14. The CMYK toner images formed in the image forming units are sequentially superimposed on the peripheral surface of the transfer belt 14 and transferred (primary transfer), so that the color toners are superimposed and formed.

  For each image forming unit, each exposure optical system 12 individually holds a light amount correction table for reducing vertical stripes, refers to the correction table according to the address in the main scanning direction, and performs PWM (Pulse Width). Exposure after correcting the light amount using Modulation). For example, PWM divides an exposure time per pixel in the main scanning direction in an electrophotography using a raster optical system.

  The color toner images are collectively transferred (secondary) to the surface of the recording paper P fed from the paper feed cassette 15 via the timing roller 16 by the discharging action having the opposite polarity to the toner of the transfer device 17. Transfer). Then, the toner is fused by the fixing device 18 in a state where the yellow toner image is the lowermost layer on the recording paper P, and the cyan toner image, the magenta toner image, and the black toner image are held in the upper layer. It turns and is discharged to the tray 19 at the top of the apparatus. The cleaning device 21 removes and cleans residual toner on the transfer belt 14 after the transfer. Although FIG. 1 illustrates an example in which the reading unit 201 and the image forming unit 202 are independent, a configuration in which the reading unit 201 and the image forming unit 202 are integrated may be employed.

[Chart installation]
Next, the installation of the chart according to the first embodiment will be described with reference to FIGS.

  FIG. 4 is a diagram illustrating an example of a chart according to the first embodiment. As shown in FIG. 4, the chart 501 is a sheet (recording medium) of the maximum size such as A3 wide 13 inches × 19.2 inches among the sheet sizes that can be output by the image forming unit 202. The chart 501 includes markers 502a, 502b, 503a, 503b, 504a, and 504b, which are position specifying information. In an area sandwiched between the markers 503a and 503b and the markers 504a and 504b, a pattern 505 represented by a uniform pseudo halftone image in any one of the CMYK colors is output. I have. Each marker, which is position specifying information, is information for specifying the position of the pattern 505 in the reading area on the document table 302.

  FIG. 5 to FIG. 10 are diagrams illustrating an installation example of the chart according to the first embodiment. For example, as shown in FIG. 5, the user installs the chart 501 so that the chart 501 fits in the reading area 601 of the document table 302. In the present embodiment, reading of the chart 501 is performed a plurality of times. The user installs and reads the chart 501 a plurality of times according to the recommended reading method displayed on the display unit 204. For example, as shown in FIGS. 6 and 7, the user installs each marker and pattern 505 included in the chart 501 so as to fit in the reading area 601. That is, as long as each marker and pattern 505 fits in the reading area 601, a part of the chart 501 does not need to fit in the reading area 601.

  For example, as shown in FIG. 8, the user rotates the chart 501 by 180 degrees and sets the chart 501 in the reading area 601. For example, as shown in FIGS. 9 and 10, the user rotates and installs the marker by an arbitrary angle within a range in which each marker is included in the reading area 601. The recommended number of times of reading the chart 501 is displayed on the display unit 204, but it depends on the performance of the image forming apparatus 100 and the like. For example, the larger the number of reading gradations, the smaller the number of times of reading the chart 501.

[Hardware Configuration of Image Forming Apparatus]
Next, a hardware configuration of the image forming apparatus 100 according to the first embodiment will be described with reference to FIG. FIG. 11 is a block diagram illustrating a hardware configuration example of the image forming apparatus 100 according to the first embodiment.

  As shown in FIG. 11, the image forming apparatus 100 includes a CPU 102, a RAM 103, a ROM 104, an external I / F 105, a display I / F 106, and an operation I / F 107. The above components are connected to each other via a bus 101.

  The CPU 102 controls the operation of the entire image forming apparatus 100. The CPU 102 controls the entire operation of the image forming apparatus 100 by executing a program stored in the ROM 104 or the like using the RAM 103 or the like as a work area. The ROM 104 stores a program for realizing the processing by the image forming apparatus 100. The RAM 103 is a work area for executing a program stored in the ROM 104 or the like. The external I / F 105 is an interface for connecting to an external device such as a PC. The display I / F 106 is an interface that controls the display unit 204 under the control of the CPU 102. The operation I / F 107 is an interface that controls the input unit 205 under the control of the CPU 102.

[Functions of Image Forming Apparatus]
Next, the function of the image forming apparatus 100 according to the first embodiment will be described with reference to FIG. FIG. 12 is a block diagram illustrating a functional configuration example of the image forming apparatus 100 according to the first embodiment.

  As shown in FIG. 12, the image forming apparatus 100 includes an image reading control unit 110 and a correction information generation unit 120. Each of the above units may be realized by software (program) or by a hardware circuit. The correction information generation unit 120 is an example of a function executed by the image processing unit 203.

  The image reading control unit 110 controls the image reading unit 301. More specifically, the image reading control unit 110 controls the image reading unit 301 that reads a chart including the pattern 505 represented by the pseudo halftone image. The number of readings and the reading method are as described above.

  The correction information generation unit 120 performs correction for correcting the light amount at the time of exposure based on a plurality of image data obtained by reading the chart 501 in which the position of the pattern 505 has been changed with respect to the reading area 601 a plurality of times. Generate information. More specifically, the correction information generation unit 120 detects each marker, which is position identification information, from the image data of the chart 501 read by the image reading unit 301 under the control of the image reading control unit 110. For example, each marker is detected using a function “findChessboardCorners ()” implemented in OpenCV (Open Source Computer Vision Library) 2.4. By using the function “findChessboardCorners ()”, the addresses (x, y) in the image data of each of the eight locations of the markers 502 a, 502 b, 503 a, 503 b, 504 a, and 504 b can be obtained. Here, x indicates an address of the image data in the main scanning direction, and y indicates an address of the image data in the sub scanning direction.

  Then, the correction information generation unit 120 superimposes a plurality of image data so that each pattern 505 matches. For example, in superimposition of image data, a rotation vector and a translation vector are obtained using a function “FindExtrinsicCameraParams2 ()” implemented in OpenCV2.4, and each pattern 505 is obtained using the obtained rotation vector and translation vector. Are superimposed so that the image data matches. Hereinafter, the superimposed image data may be referred to as “superimposed image data”. The image forming apparatus 100 repeatedly executes the above processing until the input number of readings is reached.

  Subsequently, the correction information generation unit 120 calculates an average value of luminance in the main scanning direction at an arbitrary address in the sub-scanning direction in the superimposed image data, and corrects a difference between the calculated average value and luminance in the main scanning direction. Generate correction information as a value. FIG. 13 is a diagram illustrating an example of calculating an average value of luminance in the main scanning direction according to the first embodiment. In FIG. 13, the location where the marker 502a (marker 502b) is located is above the superimposed image data, and the location where the marker 504a (marker 504b) is located is below the superimposed image data. Also, the lower right coordinate of the marker 502a is the coordinate 1, the upper right coordinate of the marker 503a is the coordinate 2, the lower right coordinate of the marker 503b is the coordinate 3, the upper right coordinate of the marker 504a is the coordinate 4, and the lower left coordinate of the marker 502b is the lower coordinate. Is coordinate 5, the upper left coordinate of marker 503b is coordinate 6, the lower left coordinate of marker 503b is coordinate 7, and the upper left coordinate of marker 504b is coordinate 8. In FIG. 13, the illustration of the pattern 505 is omitted. For example, the correction information generation unit 120 calculates the average value of the luminance in the main scanning direction at an arbitrary address y in the sub-scanning direction between the coordinate 3 of the marker 503a and the coordinate 4 of the marker 504a. Note that, in the present embodiment, the pattern 505 is a pseudo halftone image that is uniform in any one of the CMYK colors. Therefore, the correction information generation unit 120 may calculate the average value of the luminance in the main scanning direction at an arbitrary address y in the sub-scanning direction between the coordinate 7 of the marker 503b and the coordinate 8 of the marker 504b. .

  FIG. 14 is a diagram illustrating an example of the average value of the luminance change according to the first embodiment. In FIG. 14, the vertical axis represents the luminance and the horizontal axis represents the position in the main scanning direction. In FIG. 14, the solid line represents the luminance and the broken line represents the average value of the luminance change. The correction information generation unit 120 calculates the average value of the luminance change (dashed line shown in FIG. 14) from the luminance (solid line shown in FIG. 14) between the coordinate 3 of the marker 503a and the coordinate 4 of the marker 504a. In the example illustrated in FIG. 14, there are a portion having a value particularly larger than the average value of the luminance change and a portion having a particularly small value. These locations may actually appear as vertical streaks.

  FIG. 15 is a diagram illustrating an example of a halftone processed image corresponding to the luminance change illustrated in FIG. For example, as shown in FIG. 15, in the halftone processing image 1001 having the luminance change shown in FIG. 14, a portion having a luminance value particularly larger than the average value of the luminance change appears as a vertical streak 1002. Further, in the halftone processing image 1001 having the luminance change shown in FIG. 14, a portion having a luminance value particularly smaller than the average value of the luminance change appears as a vertical stripe 1003. For example, the vertical stripe 1002, which is a luminance value that is particularly larger than the average value of the luminance change, looks thin and white. In addition, for example, the vertical streak 1003, which is a luminance value particularly smaller than the average value of the luminance change, looks dark and looks like drawing a line. In the present embodiment, correction information for suppressing the appearance of such vertical streaks is generated.

  The correction information (for example, a correction table) at the address x in the main scanning direction is obtained by (Equation 1). For example, the correction information generation unit 120 calculates a difference between the obtained average value “Ave” and the luminance “p (x)” of the address x in each main scanning direction at an arbitrary address y between the coordinates 3 and 4. Is generated as the correction value “f (x)” of the light amount at the time of exposure for suppressing the appearance of each vertical streak.

  f (x) = Ave−p (x) (Equation 1)

[Correction information generation processing]
Next, the flow of the correction information generation process according to the first embodiment will be described with reference to FIG. FIG. 16 is a flowchart illustrating an example of the flow of the correction information generation process according to the first embodiment.

  As shown in FIG. 16, the image forming apparatus 100 receives an input of the number of times of reading (step S101). For example, the user refers to the recommended number of readings displayed on the display unit 204 and operates the input unit 205 to input the number of readings according to the number of gradations of reading of the image forming apparatus 100 or the like. Thereby, image forming apparatus 100 accepts an input of the number of times of reading. The user sets the chart 501 in the reading area 601 on the document table 302 while referring to the recommended reading method displayed on the display unit 204, and starts reading on the input unit 205. Perform

  Accordingly, when the image forming apparatus 100 receives an operation for starting reading (step S102: Yes), the image forming apparatus 100 reads the chart 501 set in the reading area 601 (step S103). When an operation for starting reading has not been received (step S102: No), the image forming apparatus 100 is in a state of waiting for an operation for starting reading. Then, the image forming apparatus 100 detects a marker included in the read chart 501 (Step S104). Subsequently, the image forming apparatus 100 obtains a rotation vector and a translation vector (step S105), and superimposes image data using the obtained rotation vector and translation vector so that each pattern 505 matches. It is generated (step S106).

  Thereafter, the image forming apparatus 100 determines whether or not the number of readings for which the input has been received has been reached (step S107). At this time, when the number of readings has been reached (Step S107: Yes), the image forming apparatus 100 calculates an average value of luminance in the main scanning direction at an arbitrary address in the sub-scanning direction in the superimposed image data (Step S108). . On the other hand, if the number of readings has not been reached (step S107: No), the image forming apparatus 100 returns to the processing of step S102, and executes the processing of steps S102 to S106 until the number of readings is reached. Then, the image forming apparatus 100 generates correction information using the difference between the obtained average value and the luminance in the main scanning direction as a correction value of the light amount at the time of exposure for suppressing the appearance of the vertical streak (step S109). .

[Effects of First Embodiment]
As described above, the image forming apparatus 100 reads the chart including the pattern represented by the pseudo halftone image a plurality of times after changing the position of the pattern with respect to the reading area, and obtains the plurality of charts obtained by the reading. Based on the image data, correction information for correcting the light amount at the time of exposure is generated. As a result, the image forming apparatus 100 can create suitable correction information for correcting the vertical streak of the electrophotograph caused by the charge distribution.

  For example, the number of read gradations obtained by a scanner whose read gradation number is 8 bits is 8 bits. Accordingly, in the present embodiment, the chart 501 as described above is read a plurality of times while changing the position of the pattern 505 with respect to the reading area 601 and the read image data is superimposed, thereby virtually reading the chart. Tone can be increased. Since the correction information can be generated after virtually increasing the number of tones for reading, suitable correction information for correcting, for example, vertical stripes can be obtained. The number of readings may be smaller as the number of reading gradations is larger. For example, if the number of reading gradations is 8 bits, the number of readings is about 8 times, and if the reading number of gradations is 10 bits, the scanner is 10 bits. Suitable correction information can be obtained with about six readings.

(Embodiment 2)
The embodiment of the image forming apparatus 100 according to the present invention has been described above, but may be implemented in various different forms other than the above-described embodiment. Therefore, different embodiments of (1) chart, (2) configuration, and (3) program will be described.

(1) Chart In the above-described embodiment, a case has been described in which the chart 501 including the pattern 505 represented by a uniform pseudo halftone image in any one of the CMYK colors is scanned. The chart 501 is not limited to this, and may include various other patterns 505.

  FIG. 17 is a diagram illustrating an example of a chart 501 including a pattern 505 represented by a pseudo halftone image of a plurality of colors according to the second embodiment. For example, as shown in FIG. 17, a chart 501 includes a pattern 1101 which is a pseudo halftone image of yellow, a pattern 1102 which is a pseudo halftone image of magenta, a pattern 1103 which is a pseudo halftone image of cyan, and a pseudo pseudo halftone image of black. A pattern 1104 that is a halftone image is included. As described above, by including the pseudo halftone image of a plurality of colors in the pattern 505, correction information for each color can be obtained at once. Since each pattern included in the chart 501 becomes known when a certain number of pixels are output, the address y estimated at the center of each pattern from the address (x, y) in the image between the coordinates 3 and 4 is obtained. In this case, the average value of the luminance may be obtained. By using the chart 501 including the pseudo halftone images of a plurality of colors, the operation time for generating the correction information can be reduced.

  FIG. 18 is a diagram showing an example of a chart 501 including a pattern 505 represented by a pseudo halftone image in a plurality of modes according to the second embodiment. For example, as shown in FIG. 18, the chart 501 includes pseudo halftone images of each color of CMYK for text and graphics. In FIG. 18, the pseudo cyan halftone image for character is C for character, the pseudo halftone image for magenta for character is M for character, the pseudo halftone image for yellow for character is Y for character, and the black Are represented as K for characters. Similarly, in FIG. 18, the pseudo cyan halftone image for graphics for graphics is C for graphics, the pseudo halftone image for magenta for graphics is M for graphics, and the pseudo halftone image for yellow for graphics is A pseudo halftone image for graphics Y and graphics black is represented as graphics K. By using the chart 501 including the pseudo halftone images of a plurality of modes and a plurality of colors, it is possible to reduce the working time for generating the correction information.

(2) Configuration In addition, information including processing procedures, control procedures, specific names, various data, parameters, and the like shown in the above-described documents and drawings can be arbitrarily changed unless otherwise specified. Further, each component of the illustrated apparatus is conceptual in function, and does not necessarily need to be physically configured as illustrated. That is, the specific form of the dispersion or integration of the apparatus is not limited to the illustrated one, and all or a part of the apparatus may be functionally or physically dispersed or Can be integrated.

  For example, the reading unit 201 and the image forming unit 202 may be configured by different housings. Further, for example, instead of drawing the recommended reading method or the like on the display unit 204 mounted on the image forming apparatus 100, the recommended reading method may be displayed on a display of an external device such as a connected PC.

(3) Program In one embodiment, the correction information generation program executed by the image forming apparatus 100 is a file in an installable format or an executable format as a CD-ROM, a flexible disk (FD), or a CD-R. , A DVD (Digital Versatile Disk) or other computer-readable recording medium. Further, the correction information generation program executed by the image forming apparatus 100 may be stored on a computer connected to a network such as the Internet, and provided by being downloaded via the network. Further, the correction information generation program executed by the image forming apparatus 100 may be provided or distributed via a network such as the Internet. Further, the correction information generation program executed by the image forming apparatus 100 may be provided by being incorporated in a ROM or the like in advance.

  The correction information generation program executed by the image forming apparatus 100 has a module configuration including the above-described units (the image reading control unit 110 and the correction information generation unit 120). By reading and executing the program, the above-described units are loaded on the main storage device, and the image reading control unit 110 and the correction information generation unit 120 are generated on the main storage device.

REFERENCE SIGNS LIST 100 image forming apparatus 110 image reading control unit 120 correction information generating unit

JP 2007-118194 A JP 2006-301079 A Japanese Patent No. 4994203

Claims (5)

An image reading control unit that controls an image reading unit that reads a chart including a pattern represented by a pseudo halftone image,
A correction information generation unit that generates correction information for correcting the light amount at the time of exposure based on a plurality of image data obtained by reading the chart in which the position of the pattern is changed a plurality of times with respect to a reading area; And
The chart includes position specifying information for specifying the position of the pattern in the reading area,
The pattern is represented by the pseudo halftone image in at least one or more modes for text and graphics;
The correction information generation unit superimposes a plurality of the image data so that each pattern matches based on the position identification information, and performs the correction of each of the modes based on superimposed image data obtained by superimposing a plurality of the image data. An image forming apparatus for generating information . The correction information generation unit calculates an average value of luminance in the main scanning direction at an arbitrary address in the sub-scanning direction in the superimposed image data, and corrects a difference between the calculated average value and luminance in the main scanning direction. The image forming apparatus according to claim 1, wherein the correction information is generated as a value. The pattern is represented by the pseudo halftone image of a plurality of colors,
Wherein the correction information generation unit, an image forming apparatus according to claim 1 or claim 2, characterized in that to generate the correction information for each color. Computer
An image reading control unit that controls an image reading unit that reads a chart including a pattern represented by a pseudo halftone image ,
A correction information generation unit that generates correction information for correcting the light amount at the time of exposure based on a plurality of image data obtained by reading the chart in which the position of the pattern is changed a plurality of times with respect to a reading area; Function as
The chart includes position specifying information for specifying the position of the pattern in the reading area,
The pattern is represented by the pseudo-halftone image in at least one or more modes for text and graphics;
The correction information generation unit superimposes a plurality of the image data so that each pattern matches based on the position identification information, and performs the correction of each of the modes based on superimposed image data obtained by superimposing a plurality of the image data. Generating information
A correction information generation program characterized by the following . An image reading control unit configured to control an image reading unit that reads a chart including a pattern represented by a pseudo halftone image ;
The correction information generation unit , based on a plurality of image data obtained by reading the chart in which the position of the pattern is changed a plurality of times with respect to the reading area, based on a plurality of image data, correction information for correcting the light amount at the time of exposure And generating correction information.
The chart includes position specifying information for specifying the position of the pattern in the reading area,
The pattern is represented by the pseudo halftone image in at least one or more modes for text and graphics;
In the correction information generation step, based on the position identification information, a plurality of the image data are superimposed so that each pattern matches, and the correction of each of the modes is performed based on superimposed image data obtained by superimposing a plurality of the image data. A method for generating correction information, comprising generating information.

Images